1. Field of the Invention
The present invention relates to light weight armor. More particularly, the invention relates to light weight composite armor comprising lamina-like structures arranged with zones of decreasing Young's modulus and increasing elongation characteristics so as to dissipate impact forces laterally as rapidly as possible while providing maximum missile stopping power per given weight and thickness.
2. Prior Art
Light weight composite armor is presently being utilized in military vehicles and helmuts. The armor is being used alone or in combination with surface metal structures.
U.S. Pat. No. 4,186,648 of Clusen et al describes an armor wall structure comprising a plurality of woven fabric laminates of polyester resin fibers arranged and supported in and by a resinous matrix with a filler of particulate metal abrading material, and woven fabric laminates.
U.S. Pat. No. 4,574,105 of Donovan discloses penetration resistant textile panels with plies of nylon and Kevlar.
U.S. Pat. No. 4,468,499 of Seigfried et al, which is herewith incorporated by reference, discloses chemically blended thermoplastic interpenetrating polymer network compositions.
There are many light weight materials which have high strength and elasticity but do not respond well when subjected to impact velocities over 2000 ft/sec. High modulus and high strength materials are usually brittle and crack or notch sensitive. Once damaged, these high modulus and high strength materials lose a great deal of their stoppping power or impact strength due to crack sensitivity.
Elastomer materials are not usually crack or damage sensitive but can be readily penetrated at high impact velocities.
Chopped glass fibers and most other material fillers are known to usually increase the impact resistance of resins with which they are compounded because they act as stress concentrators. However, glass fibers and fillers further tend to embrittle ductile and semiductile polymers. Addition of plasticizers and energy-absorbing constituents such as rubbers, tend to overcome the embrittlement sensitivity or crack propagation but decrease the energy dissipation away from the lateral direction and decreases penetration resistance per unit area.
Use of carbon fiber composites alone have been ineffective in providing enhanced stopping ability without an increase in mass or thickness when compared to glass fibers or aramid fiber.